Smoking during pregnancy is commonly linked to an increased chance of stillbirths as it restricts the growth of the fetus and results in placental complications.
New research in BJOG: An International Journal of Obstetrics and Gynaecology supports the hypothesis of the causal association between smoking and the risk of stillbirth.
Stillbirths occurring during the second pregnancy were studied among a total of 526, 691 Swedish women over an 18 year period from 1983 – 2001. Smoking habits during the first and second pregnancies were recorded during antenatal clinics and analysed. The effects of maternal age, mother?s educational level, cohabitation with the baby?s father, mother?s country of birth and the interval between first and second pregnancies were all included in the study, as they were regarded as risk factors in stillbirths.
Researchers concluded that maternal smoking during the first and second pregnancies results in a significant increased risk of stillbirth. The rate of stillbirth in the second pregnancy is highest at 4.1 out of every 1,000 women, amongst heavy smokers who smoked more than 10 cigarettes a day during both pregnancies.
Other factors contributing to stillbirths include lower (= 19 years) or higher (= 35 years) maternal age and long inter-pregnancy periods.
Researchers note that women who stopped smoking during the early part of their pregnancy reduced the risk of stillbirth as did those who had stopped smoking in the period from the first to the second pregnancy. Findings also suggest that a woman?s level of addiction to smoking influences the success of her smoking cessation, and the sooner she is able to stop smoking, the better it is for her and her baby.
Lovisa H?gberg from the Department of Medical Epidemiology and Biostatistics at the Karolinska Institute in Stockholm, who carried out the research said, ?This study supports that there is a causal relation between smoking and stillbirth. Heavy smokers have the most increased risk and women who quit smoking lower their risk to the same level as women who never smoked during pregnancy.?
?Smoking during pregnancy is a preventable cause of stillbirth, it is therefore important to encourage all pregnant women to quit. Smoking is also known to increase the risk of other adverse pregnancy outcomes.?
Professor Philip Steer, BJOG editor-in-chief said, ?We know of the harmful effects of smoking on the fetus because of the direct exposure to toxins when cigarette smoke is inhaled by the mother. The chance of having a tragic stillbirth can therefore be reduced and prevented.?
?It is obvious that pregnant women need to stop smoking if they want a healthy baby and it is the duty of doctors and midwives, and more importantly, the mothers themselves, to ensure that they quit.?